Starvation Mode and Plateaus, what is the real story?

Ok, I know this can be a touchy subject but there must be some answer here.

In another thread someone said this:

"If you are at a caloric deficit, it is impossible to not LOSE weight. Law of thermodynamics applied to weight loss is relevant"

Now if this is true than Starvation mode and Plateaus can not be true.

I find this odd since I read about many people on this site that have actually increased their calories and lost more weight than before. And there are still more people on here who maintain a deficit yet see no weight loss at all.

What is the real story here?

A long-term caloric deficit changes your maintenance level intake via weight fluctuations and hormonal imbalances such as changes in thyroid and potentially leptin, and subsequently your maintenance level calories drops. Hence plateaus. The same caloric deficit that got you from 250 pounds to 220 pounds probably won't get you to 150 pounds from 170 pounds.

This does not defy the law of thermodynamics, it merely illustrates that your maintenance intake will fluctuate based on various factors such as weight/lean body mass.

Good info above. I can add also the process of starvation mode if you would like to see.

The process.

The body uses glucose as its main metabolic fuel if it is available. About 20% of the total energy consumption occurs in the brain. The rest of the glucose consumption fuels muscle tissue and red blood cells.

Glucose can be obtained directly from dietary sugars and carbohydrates. In the absence of dietary sugars and carbohydrates, it is obtained from the breakdown of glycogen. Glycogen is a readily-accessible storage form of glucose, stored in small quantities in the liver and muscles. The body's glycogen reserve can provide glucose for about 6 hours.

After the glycogen reserve is used up, glucose can be obtained from the breakdown of fats. Fats from adipose tissue are broken down into glycerol and free fatty acids. Glycerol can then be used by the liver as a substrate for gluconeogenesis, to produce glucose.

Fatty acids can be used directly as an energy source by most tissues in the body, except the brain, since fatty acids are unable to cross the blood-brain barrier. After the exhaustion of the glycogen reserve, and for the next 2-3 days, fatty acids are the principal metabolic fuel. At first, the brain continues to use glucose, because, if a non-brain tissue is using fatty acids as its metabolic fuel, the use of glucose in the same tissue is switched off. Thus, when fatty acids are being broken down for energy, all of the remaining glucose is made available for use by the brain.

However, the brain requires about 120 g of glucose per day (equivalent to the sugar in 3 cans of soda), and at this rate the brain will quickly use up the body's remaining carbohydrate stores. However, the body has a "backup plan," which involves molecules known as ketone bodies. Ketone bodies are short-chain derivatives of fatty acids. These shorter molecules can cross the blood-brain barrier and can be used by the brain as an alternative metabolic fuel.

After 2 or 3 days of fasting, the liver begins to synthesize ketone bodies from precursors obtained from fatty acid breakdown. The brain uses these ketone bodies as fuel, thus cutting its requirement for glucose. After fasting for 3 days, the brain gets 30% of its energy from ketone bodies. After 4 days, this goes up to 70%.

Thus, the production of ketone bodies cuts the brain's glucose requirement from 120 g per day to about 30 g per day. Of the remaining 30 g requirement, 20 g per day can be produced by the liver from glycerol (itself a product of fat breakdown). But this still leaves a deficit of about 10 g of glucose per day that must be supplied from some other source. This other source will be the body's own proteins.

After several days of fasting, all cells in the body begin to break down protein. This releases amino acids into the bloodstream, which can be converted into glucose by the liver. Since much of our muscle mass is protein, this phenomenon is responsible for the wasting away of muscle mass seen in starvation.

However, the body is able to selectively decide which cells will break down protein and which will not. About 2–3 g of protein has to be broken down to synthesise 1 g of glucose; about 20–30 g of protein is broken down each day to make 10 g of glucose to keep the brain alive. However, this number may decrease the longer the fasting period is continued in order to conserve protein.

Starvation ensues when the fat reserves are completely exhausted and protein is the only fuel source available to the body. Thus, after periods of starvation, the loss of body protein affects the function of important organs, and death results, even if there are still fat reserves left unused. (In a leaner person, the fat reserves are depleted earlier, the protein depletion occurs sooner, and therefore death occurs sooner.)

The ultimate cause of death is, in general, cardiac arrhythmia or cardiac arrest brought on by tissue degradation and electrolyte imbalances.

I guess my question for Chuck is....


Are you planning on trying to maintain an extreme caloric deficit for an extended period of time, or is this out of general curiosity?

I believe in starvation mode 100%. If you don't, then explain to me how it is physically possible for me to eat only about 1700 calories a day, burn 3500 calories a week by exercise, and not lose a pound. I was fairly diligent about tracking my calories consumed, and I wasn't even counting calories burned lifting weights. I did this for about 2 months and lost about 1 lb.

Now, I am an engineer and am quite familiar with the laws of physics and thermodynamics, and I know this is not possible from a calorie point of view. There HAD to have been something else going on.

This make perfect sense to me, as you lose more weight, you must change your intake to match your new maintenance level. The problem is, starvation mode, as I understand it says that if you maintain too much of a deficit for a period of time you will stop losing and possibly even gain weight.

I am not saying this is true, but i did believe it at some point but now i am in doubt.

Everyone's definition for 'starvation mode' differs. How are you defining it?

I believe in starvation mode 100%. If you don't, then explain to me how it is physically possible for me to eat only about 1700 calories a day, burn 3500 calories a week by exercise, and not lose a pound. I was fairly diligent about tracking my calories consumed, and I wasn't even counting calories burned lifting weights. I did this for about 2 months and lost about 1 lb.

Now, I am an engineer and am quite familiar with the laws of physics and thermodynamics, and I know this is not possible from a calorie point of view. There HAD to have been something else going on.

Was 1,700 calories a proper deficit for you? Were you weighing all your food with scales, measuring cups/spoons, etc.? How did you calculate your maintenance?

The starvation mode I am referring to is the concept that if you don't eat enough calories you will stop losing and possibly even gain weight.

And I'm going to assume you draw a distinction between starvation mode and the natural, long-term change (reduction) in maintenance that occurs via processes explained previously, correct?